Treating cotton goods



Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE TREATING COTTON GOODS No Drawing.

Application April 14, 1938,

Serial No. 202,009

2 Claims.

This invention relates to improvements in the processing of cotton containing textiles. More particularly this invention relates to improvements in the processing of cotton cloth or cloth containing a high proportion of cotton whereby the material is pretreated in a manner which renders it more amenable to the action of the customarily employed scouring and bleaching agents.

According to current practice in the processing of cotton cloth preparatory to dyeing and finishing, the partially treated cloth is scoured and then bleached. The scouring is accomplished by suitable detergents Which among other things improve the absorbency of the fiber for the bleaching solution. The cloth, as it reaches the bleaching, frequently contains foreign materials such as motes, that is small particles of cotton seed or like substances which have remained attached to the fibers. As a result, in order to soften and remove these motes and other foreign substances, the bleaching treatment must be made more severe than is required merely to attain the desired color. This required increase in the severity of the bleaching treatment is accompanied by reaction with the fiber itself with consequent degradation and loss of strength and material. In the past the pretreatment of certain types and Weights of cotton materials has sometimes included a step known as kier boiling. This treatment involves the boiling of the cotton goods in a dilute caustic solution prior to the bleaching stage. The usefulness of such a treatment has been limited, however, by the fact that the drastic boiling in the kier weakens the fibers and results in a marked loss of tensile strength, and also by the fact that it is only applicable to light weight cotton materials. Heavier materials and materials containing rayon are not amenable to kier boiling due to the resultingundesirable scuffing of the surface threads. Such materials are included in those which may be treated successfully by the process of my invention.

I have found that the above referred to difficulties may be overcome by exposing the cotton containing cloth to the action of an aqueous caustic soda solution at moderate temperatures for a substantial period of time. By such a pretreatment, in accordance with the process of my invention, the motes and other foreign substances are softened and modified so that they are readily removed from the fabric by subsequent scouring and bleaching operations. This pretreatment has the added advantage that the time for and necessary severity of the scouring and bleaching treatments may be greatly reduced with a consequent reduction in the degradation of the fiber and loss of material which necessarily accompany the scouring and bleaching operations when they are conducted in a manner designed to soften and remove such foreign substances in addition to their normal functions. By such a pretreatment, the overall time required for the processing of the material is reduced. A further important advantage resident in the caustic soda pretreatment of the present invention is the fact that decreased quantities of detergent and bleaching materials are required in the subsequefnt scouring and bleaching treatments.

In accordance with my invention the cotton cloth to be processed is laid out and sewn into convenient lengths and singed if required. It is then saturated or impregnated with a dilute aqueous solution of sodium hydroxide and allowed to remain in contact with this solution at room temperature for a period ranging from 2 to 12 hours, depending upon the quantity and characteristics of the motes and other foreign substances present. The exposure to the action of the dilute caustic solution is conveniently carried out over night. The fabric is conveniently saturated with caustic solution by passing it into or thru the solution. While the cloth may remain immersed in the solution for the required period, I prefer to accomplish the referred to impregnation by passing the cloth thru the solution and then to remove the excess caustic solution by passing the cloth thru a squeeze roll or similar device. The cloth is then acted upon during the period of standing by the solution which has adhered thereto. Following the period of exposure to the alkaline solution the cloth may be washed and is then subjected to a scouring treatment. In most cases, however, washing at this stage is not necessary since the small amount of alkali present in the cloth will not hinder the detergent action and may even assist in the scouring action. The material after the caustic treatment is placed in a jig or dolly and scoured with any suitable detergent solution. As a result of the caustic pretreatment the total time required for scouring is substantially reduced, for example, to approximately 3 hours instead of a '5 hour or longer period. The material is then washed and bleached with any desired bleaching agent such as, for example, a hypochlorite or a peroxide/The motes and other foreign bodies having been previously softened and partially removed by the alkaline treatment, the amount of bleaching agent used and the time of treatment, that is the severity of the bleaching, may be decreased. The successive operations, following the bleaching stage, are the same as in conventional practice. The concentration of the alkaline solution in which the material is soaked according to my invention may vary up to about grams per liter. I have found that a solution having a concentration of approximately 20-30 grams NaOI-I per liter gives advantageous results in most cases.

Some cotton containing materials to be secured and bleached contain a substantial proportion of starch as a residue from previous operations. It is often desired to remove this starchy material by solubilizing it by treatment with a starch solubilizing enzyme. My process may by used in conjunction with this additional treatment for the removal of starch. In such a case, the cloth is first treated with an appropriate enzyme, such as for example diastafor, i. e., a diastase product, for an appropriate period of time followed by a thorough rinsing to remove the solubilized starch. The above described dilute alkali treatment of my invention advantageously follows this step.

Operation in accordance with the present invention possesses the additional advantage that in the case of certain types of fabric, the reduction in the time of securing resulting from the caustic pretreat tends to decrease a difliculty generally referred to as rope marks. In handling the heavier type of fabric in the form of a rope the cloth tends to develop creases and a crumpled appearance which is very diflicult to remove. Ap-

parently due to the decreased time that the cloth is in such a wadded condition when treated in accordance with my invention, these rope marks are minimized. At present, various types of heavy cloth are not treated in this way, because of the just described undesirable effects, but are spread out and treated while open. Due to the decreased tendency to form rope marks when employing the present invention,'certain heavier materials may be treated in the form of a rope rather than in a spread out form which would otherwise be employed for their treatment.

I claim:

1. In the process of treating unfinished cotton containing goods in which the goods are scoured and thereafter bleached, the improvement which comprises treating the cotton containing material prior to the securing operation to soften and remove motes and foreign substances by exposing it to the action of an aqueous solution of sodium hydroxide having a concentration of from about 20 to 100 grams per liter at a moderate temperature for from about 2 to 12 hours.

2. In the process of treating unfinished cotton containing goods in which the goods are scoured and thereafter bleached, the improvement which comprises treating the cotton containing material prior to the scouring operation to soften and remove motes and foreign substances by exposing it to the action of an aqueous solution of sodium hydroxide having a concentration of from about 20 to 30 grams per liter at a moderate temperature for from about 2 to 12 hours.

ARCHIE LOUIS DUBEAU. 

